/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package com.sun.org.apache.xml.internal.security.utils;


/**
 * A Factory to return an XPathAPI instance. If Xalan is available it returns XalanXPathAPI. If not,
 * then it returns JDKXPathAPI.
 */
public abstract class XPathFactory {

  private static boolean xalanInstalled;

  static {
    try {
      Class<?> funcTableClass =
          ClassLoaderUtils.loadClass("com.sun.org.apache.xpath.internal.compiler.FunctionTable",
              XPathFactory.class);
      if (funcTableClass != null) {
        xalanInstalled = true;
      }
    } catch (Exception e) {
      //ignore
    }
  }

  protected synchronized static boolean isXalanInstalled() {
    return xalanInstalled;
  }

  /**
   * Get a new XPathFactory instance
   */
  public static XPathFactory newInstance() {
    if (!isXalanInstalled()) {
      return new JDKXPathFactory();
    }
    // Xalan is available
    if (XalanXPathAPI.isInstalled()) {
      return new XalanXPathFactory();
    }
    // Some problem was encountered in fixing up the Xalan FunctionTable so fall back to the
    // JDK implementation
    return new JDKXPathFactory();
  }

  /**
   * Get a new XPathAPI instance
   */
  public abstract XPathAPI newXPathAPI();

}
